Being effective with it doesn't mean just shooting it. You need to know how to field strip it. Properly clean it. Clear a a jam. Make repairs. And owning guns and playing video games doesn't mean ****. just cause you can shoot a gun on full auto accurately in a games doesn't mean you can do it in real life.

By "be effective" I mean hit a target. In zombie apocalypse I'd be more concerned with your ability to actually hit the zombies than clean the gun.

And I didn't say you could play video games and all of a sudden put Navy SEALs to shame as soon as you pick up a gun the first time, but the experience, or at the very least, the knowledge of how it works, how to reload it, and how to use sights, are already developed in people who know games.